Abyssal Drain spam is stronger and more spammable than Steel cyclone spam; unless it's being boosted by IR.
and IR is limited to 90 second time frames while blood weapon is only limited to 40 second ones and lasts longer than IR does; every 2nd of which could be extended by Delirium. You'd essentially give DRK a near-hallowed ground on every single multi-pull in level 60+ dungeons in the game, whereas WAR still has to choose which packs to use IR on due to its recast timer, on top of not being able to use it against bosses while DRK's single target rotation against bosses would be near-unaffected.
That's also before taking into account that the DRK would be getting full damage from their abilities, while that same IR used to self sustain <could> have been used to 5x decimate instead.
IR may be extremely powerful; but it has its own disadvantages. A theoretical Abyssal drained boosted blood weapon would crush IR out the window on self-sustain; no need to make something epically overpowered in response to one thing being super strong.
